In recent years, along with rapid popularization of communication infrastructures and outstanding increase in the performance of information processing such as of computers, it has been demanded to increase the operation speed, as well as decrease the size and the cost for optical transmission and receiving equipments or optical switches. Under the background described above, development has been conducted vigorously for silicon photonics that realize optical parts by using silicon materials instead of compound semiconductors typically represented by GaAs and InP used so far.
For optical parts such as optical waveguides and optical synthesizers/branchers, operation in the use of the silicon material has already been confirmed. However, since silicon is an indirect transition type semiconductor, it is difficult to amplify light. While Intel Co. in USA has announced a silicon laser having a Raman effect (Nature 433, 725-728 (2004)), it involves a problem that incidence of a laser light from the outside is necessary.